The present invention relates to a new form of Pennisetum alopecuroides plant named ‘Red Rocket’. ‘Red Rocket’ is a seedling of an unnamed Pennisetum alopecuroides, not patented, characterized by thick greyed-purple inflorescences on 75 cm stems that start in early September in northern Illinois. The new plant is the result of a breeding program taking place at a wholesale perennial nursery since 2001. The seedling was grown by the inventor at a wholesale perennial nursery in Hebron, Ill. in 2010. The selection of the new plant was due to its thick greyed-purple inflorescences on 75 cm stems that start in early September in northern Illinois. Asexual, vegetative division propagation has been the only means of reproduction. Propagation has taken place at a wholesale perennial nursery Hebron, Ill. in 2011. To date these plants have remained uniform in height. The new Pennisetum has shown to be stable and identical in reproduction to the parent after making over 550 vegetative divisions from 2011 to 2013.